Maand: juli 2021

Dipoles are a classic builder’s antenna, after all they are usually little more than two pieces of wire and a feedline. But as [Rob] shows us in the video below, there are a few things to consider.

The first thing is where to get the wire. A damaged extension cord donated the wire. That’s actually an interesting idea because you get multiple wires the same length inside the extension cord. Of course, it is easy to just pull the conductors out of the extension cord, but how do you feed it? A small balun converts the unbalanced feed line into a balanced connection for the antenna. Although the title says “free dipole” this balun is commercial and probably cost something unless you happen to already have one. However, building a balun isn’t all that tricky, either if you happen to have a ferrite toroid.

If you want to transmit, you’ll probably need a little different arrangement, but for receiving this will definitely get the job done. A tuner would make life easier.

Even though this is technically a dipole, without tuning it is more of a random wire. However, it works and with antenna analyzers now common gear, it would be easy to shorten the dipole down to any band you wanted.

Of course, in the mechanical world, they say if you can’t make it exact, make it adjustable. If you are looking for cheap station gear, there’s always the $50 ham, otherwise known as [Dan Maloney].

We don’t normally embrace the supernatural here at Hackaday, but when the topic turns to the radio frequency world, Arthur C. Clarke’s maxim about sufficiently advanced technology being akin to magic pretty much works for us. In the RF realm, the rules of electricity, at least the basic ones, don’t seem to apply, or if they do apply, it’s often with a, “Yeah, but…” caveat that’s sometimes hard to get one’s head around.

Perhaps nowhere does the RF world seem more magical than in antenna design. Sure, an antenna can be as simple as a straight piece or two of wire, but even in their simplest embodiments, antennas belie a complexity that can really be daunting to newbie and vet alike. That’s why we were happy to recently host Karen Rucker’s Introduction to Antenna Basics course as part of Hackaday U.

The class was held over a five-week period starting back in May, and we’ve just posted the edited videos for everyone to enjoy. The class is lead by Karen Rucker, an RF engineer specializing in antenna designs for spacecraft who clearly knows her business. I’ve watched the first video of the series and so far and really enjoy Karen’s style and the material she has chosen to highlight; just the bit about antenna polarization and why circular polarization makes sense for space communications was really useful. I’m keen to dig into the rest of the series playlist soon.

The 2021 session of Hackaday U may be wrapped up now, but fear not — there’s plenty of material available to look over and learn from. Head over to the course list on Hackaday.io, pick something that strikes your fancy, and let the learning begin!